Two prisoners, one a convicted rapist and the other an alleged armed robber, broke out of a Serco prison van at Geraldton airport as they were being taken to maximum security prisons in Perth.

The pair were on the run for 36 hours until a massive manhunt, which involved more than 100 police officers, recaptured them in bush north of Mullewa.

Mr Francis, who has spoken of his growing concerns with the performance of Serco which holds the contract to run WA's prison transport services, said it had yet to be ascertained whether Serco had been at fault under its contract.

"We need to wait until everything is worked out," he said. "It looks like it was human error but it may well be a mechanical fault and that's something else that needs to be addressed."

Mr Francis said that as part of its contract Serco was also responsible for the upkeep of WA's prison van fleet, which was replaced after the death of Mr Ward.

The Aboriginal elder died from heat stroke after he was held in the back of a prison van that was not air-conditioned in 2008, when the custodial services contract was held by G4S.

Mr Irwin was again unavailable yesterday to talk about the botched prison transfer, during which the prisoners stole a car from a nearby hire car agency at the airport to hasten their escape.

"Serco meets regularly with Government customers in WA," a company spokesman said yesterday. "These meetings are part of our rigorous reporting and review program."

The prison van breakout last week also revealed that escapee Cameron John Graham had been given a temporary transfer to Greenough Regional Prison to facilitate family visits over the Christmas period.

In November Graham was sentenced to 11 years jail for the brutal rape of a woman. Less than two months later, he was given the privilege of the temporary transfer.

The Department of Corrective Services has been unable to say this week how many other prisoners were given a temporary transfer last month. It has also refused to reveal the policy or guidelines for determining temporary transfer requests, and who would make those decisions.

Mr Francis has said he will also investigate allegations of seemingly exorbitant "out-of-contract" prisoner movements quotes and costs.